Boom assemblies are commonly used on agricultural vehicles or towed implements (e.g., sprayers or planters, etc.) to dispense seed, fertilizer, insecticide, herbicide, etc. and other miscellaneous agricultural materials. The typical boom assembly is configured to pivot or fold between operative and inoperative positions relative to the boom support vehicle. In an operative position, the boom assembly commonly extends in a laterally outward direction from the boom support vehicle up to a distance of ninety feet or larger such that the agricultural applicator covers a large surface area with each pass across a field. The weight of the boom assembly generally correlates with its operative length.
Upon completing distribution of the agricultural materials to the field, a conventional pivot mechanism (e.g. hydraulic, pneumatic, etc.) is employed to swing, pivot or fold each of the booms to a folded position for transport. The preferred folded position of the boom assembly is generally parallel to the direction of travel of the support vehicle such that each of the booms and the support vehicle has a narrow profile for ready transport from the field to a roadway.
Typical boom assemblies include a left and right boom each pivotal about a stationary, central mainframe structure. Dual-stage folding boom assemblies comprise left and right booms each having an outer section and an inner section. Each outer and inner section is pivotal about a primarily vertical axis between an extended and a folded position. The outer section folds inward onto the inner section, and the inner section folds inward alongside the stationary mainframe structure of the agricultural implement to a stowed position on a cradle support structure ready for transport. With larger boom assemblies (e.g., each boom longer than one-hundred feet), each left and right boom typically includes three sections (outer, middle, inner) that requires three folding stages: the first stage includes the outer section folding onto the middle section, the second stage includes the outer and middle sections folding onto the inner section, and the third stage includes all three sections folding onto the cradle support structure at the mainframe of the agricultural implement. For booms that require three folding stages, the folding stages should be sequenced for the booms to fold and unfold properly. The first and second folding stages are typically controlled by a first hydraulic circuit, and the third folding stage is controlled by a second hydraulic circuit. The first folding stage typically folds first because the outer boom section is usually the lightest of the multiple boom sections, associated with the convention tapered shaped of the boom, and so does not require sequencing.
However, these certain known multiple-stage folding boom assemblies have drawbacks. For example, the outer boom section is known to unfold before the second folding stage is complete. In addition, gravitational effects are known to cause the outer section to fall out of alignment from being received by the cradle support structure for transport.
Therefore, there is a need or desire for a lock assembly that overcomes the foregoing difficulties and drawbacks of the prior art. The lock assembly should also be automatic, simple and reliable to operate, and economical to manufacture. In addition, the lock assembly should be configured to be utilized with a wide variety of vehicles or towed implements in addition to those related to agricultural sprayers.